From the music news Web site the Daily Swarm:

Barack Obama, the presumptive Democratic presidential nominee, has left a slot open in his schedule during the first weekend of August for an appearance at the Lollapalooza music festival in his hometown of Chicago, according to multiple sources familiar with the ongoing planning and logistics.

No official confirmation from the Obama camp, but the Daily Swarm goes on to highlight several of the senator's connections to artists on the Lollapalooza bill. The festival moves into Grant Park Aug. 1-3.